1. Field of the Invention
The present invention relates to a servo data writing apparatus for writing servo data on a disk of a hard disk drive, and method of writing servo data on a disk, more specifically to a servo data writing apparatus which can write servo data on the disk while suppressing the vibration caused by the rotation mechanism as it rotates, and a method therefor.
2. Description of the Related Art
A conventional compact hard disk drive has a structure as shown in FIG. 1, in which a disk 2, a head 3, a head movement mechanism (or carriage mechanism) 4, a disk rotation mechanism 7, and the like are housed in a metal-made case 1. The case 1 is closed by a top cover 5. The top cover 5 can be set on or removed from the case with fixation screws. A disk 2 is fixed in the disk rotation mechanism 7. The disk rotation mechanism 7 rotates the fixed disk 2 at a high speed. In order to achieve the high-speed rotation, a spindle motor which will be described later is provided in the disk rotation mechanism 7. The head movement mechanism 4 includes a swing arm 4a for moving the head 3 above the disk 2 via a suspension 3a, a voice coil motor 4b for swinging the swing arm 4a in the radial direction of the disk 2, a rotation shaft 4c for supporting the swing arm 4a and the like.
FIG. 2A is a cross section of the vicinity of the disk rotation mechanism in the HDD from which the top cover is removed. As shown in this figure, the disk rotation mechanism 7 includes a disk press member 7a, a rotation shaft 7b, a bearing 7c, a tapped hole 7d, a hub 7e, a spacer ring 7f, a spindle motor 7g, and the like. The hub 7e fixes, for example, three disks 2. The spacer ring 7f mounted to the hub 7e serves to maintain an axial-directional distance between each adjacent pair of disks 2, at constant. The disk press member 7a presses the disks and the spacer ring 7f in the axial direction. The rotation shaft 7b is supported by the bearing 7c. A tip end of the free end side of the rotation shaft 7b has a tapped hole 7b formed such as to be engaged with one of fixation screws 6 when the top cover is set. The spindle motor 7g rotates the hub 7e on which the disks 2 and the like are set, around the rotation shaft 7b.
FIG. 2B is a cross section of the vicinity of the disk rotation mechanism in the HDD to which the top cover 5 is set. As shown in this figure, when the top cover 5 is set, one of the fixation screws 6 is engages with the tapped hole 7d of the rotation shaft 7b. In this case, the tip end portion of the free end side of the rotation shaft 7b is fixed by the top cover 5, and therefore the non-repeatable vibration of the rotation shaft 7b caused by the rotation of the spindle motor 7g is suppressed.
FIG. 3A is a cross section of the vicinity of the head movement mechanism in the HDD from which the top cover is removed 5. As shown in this figure, the head movement mechanism 4 includes, in addition to the swing arm 4a and the voice coil motor 4b, a rotation shaft 4c, a bearing 4d, a tapped hole 4e, and the like. The rotation shaft 4c is supported by the bearing 4d. A tip end of the free end side of the rotation shaft 7b has a tapped hole 4e formed such as to be engaged with one of fixation screws 6 when the top cover is set. The voice coil motor 4b rotates the swing arm 4a around the rotation shaft 4c.
FIG. 3B is a cross section of the vicinity of the head movement mechanism in the HDD to which the top cover 5 is set. As shown in this figure, when the top cover 5 is set, one of the fixation screws 6 is engages with the tapped hole 4e of the rotation shaft 4c. In this case, the tip end portion of the free end side of the rotation shaft 4c is fixed by the top cover 5, and therefore the non-repeatable vibration of the rotation shaft 4c caused by the rotation of the spindle motor 7g is suppressed.
During the manufacture of an HDD, usually, a process for writing servo data used for controlling the positioning of the head 3 is carried out. FIG. 4 is a perspective view illustrating that the servo data is written on a disk 2. In the case where the sector servo mode is employed, a user area for recording user data and a servo area for recording servo data are provided on the data surface of the disk 2. When servo data is written, an exclusive servo data writing apparatus, which is a so-called Servo writer, is generally used. A base (not shown) for fixing the case 1 of the HDD is provided for the servo writer. The servo writer writes servo data at a predetermined position of the disk 2 by using the head movement mechanism 4 built in the HDD.
Further, the servo writer includes a clock head 10 and a positioning actuator mechanism 11. The clock head 10 records a reference clock necessary for writing the servo data, on the disk 2. The clock head 10 is supported by the suspension 10a. The suspension 10a is mounted to a clock head supporting mechanism (not shown). Meanwhile, the positioning actuator mechanism 11 positions the head 3 at a position to which the servo data is to be recorded. A positioning pin 11a is provided for the positioning actuator mechanism 11. The positioning pin 11a positions the head 3 supported by the suspension 3a, to a predetermined position by guiding the swing arm 4a.
There are several techniques for writing servo data by means of a servo writer. According to the first technique, a writing process is carried out directly on a disk when the top cover is removed from the HDD as can be seen in FIG. 4. That is, servo data is written while the tip portion of the free end side of the rotation axis 7b in the disk rotation mechanism is released (to be called one-end supporting state, hereinafter). In this case, the top portion of the free end side of the rotation shaft 7b is not supported, and therefore the non-repeatable vibration of the rotation shaft 7b caused by the rotation of the spindle motor 7g is enhanced. In similar manner, the tip portion of the free end side of the rotation shaft 4c is not supported, and therefore the non-repeatable vibration of the rotation shaft 4c which supports the swing arm 4a is enhanced. Consequently, servo data containing a large amount of vibration component is written on the disk 2. As a result, the positioning accuracy of the case where the positioning control of the head 3 is actually carried out after the writing of the servo data based on the servo data recorded on the disk 2, is deteriorated.
According to the second technique, a dummy cover 12, which substitutes for the top cover, is mounted on the HDD. The dummy cover 12 is fixed to the case 1 by a plurality of fixation screws 12a. One of the fixation screws 12a is engaged with the tapped hole 7d provided in the rotation shaft 7b. Therefore, similar to the case where the top cover is set, servo data is written while the tip portion of the free end side of the rotation shaft 7b is supported (to be called a both-end supporting state). Consequently, the non-repeatable vibration of the rotation shaft 7b is suppressed. Meanwhile, when the dummy cover 12 is mounted as shown in FIG. 5B, the rotation shaft 4c can be held in the both-end supporting state. Thus, the non-repeatable vibration of the rotation shaft 4c is suppressed, and the servo data can be written at a high accuracy. However, in this technique, the operation of setting and removing the dummy cover 12, which is time-and-labor consuming, is required. Further, during the setting or removing operation, dust is likely to enter the HDD.
Lastly, according to the third technique, the writing operation is carried out while the top cover 5 is set. In this case, openings 13a and 13b are provided in the top cover 5 so that the clock head 10 and the positioning pin 11a are able to move within a predetermined region. With this structure, the writing of the servo data can be carried out while the rotation shaft 7b and the rotation shaft 4c are in the both-end supporting state. However, in this technique, the strength of the top cover 5 is decreased because of the openings 13a and 13b. Therefore, the non-repeatable vibration of the rotation shaft 7b and the rotation shaft 4c cannot be sufficiently suppressed. Further, after the completion of the writing of servo data, the openings 13a and 13b must be sealed.